0620_w14_qp_23
A paper of Chemistry, 0620
Questions:
7
Year:
2014
Paper:
2
Variant:
3
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1
The structures of fi ve substances, A, B, C, D and E, are shown below. Br – Br – K+ Br – K+ K+ Br – Br – K+ Br – K+ K+ A B C D E S S S S S S S S O C O C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C F F F F F F S Answer the following questions about these substances. Each substance may be used once, more than once or not at all. Which two substances are elements? and Which substance has a giant ionic structure? Which substance is a product formed when a hydrocarbon is completely burnt in air? Which substance, when molten, produces a brown vapour at the anode when electrolysed? Which substance is used as a lubricant? Deduce the simplest formula of substance A. Calculate the relative molecular mass of substance E. You must show your working.
2. Atoms, elements and compounds  →  2.5. Simple molecules and covalent bonds
11. Organic chemistry  →  11.5. Alkenes
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2
Use ideas about the movement and arrangement of particles to explain why: ● solids have a definite volume and shape, ● liquids have a definite volume but no definite shape, ● gases have no definite volume or shape. The table shows some properties of six substances, A to F, which are either solids or liquids at room temperature. substance melting point / °C electrical conductivity solubility in water A +3550 does not conduct in any state insoluble B +44 does not conduct in any state insoluble C +1660 conducts when solid or liquid insoluble D +681 only conducts when in aqueous solution or liquid soluble E –39 conducts when solid or liquid insoluble F –11 does not conduct in any state insoluble Which substance has a giant covalent structure? Which two substances are liquids at room temperature? Which two substances are metals? Which two substances are simple molecules? Dry air contains mainly nitrogen, noble gases and oxygen. Which one of the following shows the correct composition of dry air? Tick one box. nitrogen 21%, oxygen 78%, noble gases 1% nitrogen 1%, oxygen 78%, noble gases 21% nitrogen 69%, oxygen 21%, noble gases 10% nitrogen 78%, oxygen 21%, noble gases 1% Metals can be joined together by high temperature welding. This process is sometimes carried out in the presence of argon. Suggest why welding is carried out in the presence of argon.
1. States of matter  →  1.1. Solids, liquids and gases
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3
Rhubarb is a plant which has a red stem. A student separated the pigments in the rhubarb stem by chromatography. He used the apparatus shown below to extract the pigments. solvent A pieces of rhubarb State the name of the piece of apparatus labelled A. Suggest a suitable solvent, other than water, that he could use to extract the pigments. The solution of pigments was not concentrated enough to use for chromatography. Suggest how the student could make the solution more concentrated. The student carried out chromatography using the apparatus shown below. chromatography paper chromatography jar lid for chromatography jar solvent Y Z A spot of the pigment mixture was placed at Y. Explain why a spot of the mixture was not placed at Z. Describe how the rest of the procedure was carried out. Rhubarb leaves contain ethanedioic acid. The structure of ethanedioic acid is shown below. C C O O O O H H On the structure above, put a ring around a carboxylic acid group. Deduce the molecular formula of ethanedioic acid. A teacher heated ethanedioic acid with concentrated sulfuric acid. The equation for the reaction is: COOH COOHH2SO4 CO+ CO2+ X Deduce the formula of compound X. At the end of the reaction, the contents of the test-tube contained diluted sulfuric acid only. Explain why. Carbon dioxide is a product of this reaction. State one common source of the carbon dioxide in the atmosphere. Explain why an increase in the concentration of carbon dioxide in the atmosphere is harmful to the environment.
12. Experimental techniques and chemical analysis  →  12.3. Chromatography
11. Organic chemistry  →  11.7. Carboxylic acids
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4
A mixture of soil and water was shaken and then fi ltered. Draw a labelled diagram of the apparatus you would use for separating the insoluble particles of soil from the solution. The fi ltrate was then evaporated. The table shows the composition and mass of each compound obtained by evaporating the fi ltrate. compound ions present in the compound mass of compound / g calcium carbonate Ca2+ and CO3 2– 4.0 calcium sulfate Ca2+ and SO4 2– 5.0 magnesium sulfate Mg2+ and SO4 2– 2.8 K+ and NO3 – 1.2 potassium sulfate K+ and SO4 2– 2.4 sodium carbonate 3.0 sodium chloride Na+ and Cl – 1.6 State the name of the compound which contains K+ and NO3 – ions. Write the symbols for the ions present in sodium carbonate. Which compound with a singly charged negative ion has the highest mass in the mixture? The table from page 7 is repeated below: compound ions present in the compound mass of compound / g calcium carbonate Ca2+ and CO3 2– 4.0 calcium sulfate Ca2+ and SO4 2– 5.0 magnesium sulfate Mg2+ and SO4 2– 2.8 K+ and NO3 – 1.2 potassium sulfate K+ and SO4 2– 2.4 sodium carbonate 3.0 sodium chloride Na+ and Cl – 1.6 Calculate: the total mass of all the compounds present in the mixture, the percentage of magnesium sulfate by mass in the mixture. Calcium carbonate decomposes when heated. Complete the symbol equation for this reaction. CaCO3 → CaO + Calcium oxide, CaO, reacts with water to form a strongly alkaline solution. Which one of the following pH values is strongly alkaline? Put a ring around the correct answer. pH 3 pH 7 pH 8 pH 12
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
9. Metals  →  9.4. Reactivity series
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5
Methanol reacts with excess hydrochloric acid to form chloromethane and water. methanol + hydrochloric acid → chloromethane + water To which homologous series does methanol belong? Complete the structure of methanol below to show its functional group. C H H H Methanol can be made from synthesis gas which contains carbon monoxide and hydrogen. Synthesis gas is made from methane. Complete the symbol equation for this reaction. CH4 + H2O → CO + H2 Suggest two hazards associated with the products of this reaction. A student investigated the rate of reaction of methanol with hydrochloric acid. The graph below shows how the concentration of hydrochloric acid changes with time. 1.0 0.8 0.6 0.4 0.2 0.0 time / hours concentration of HCl in mol / dm3 Describe how the concentration of hydrochloric acid changes with time. Deduce the concentration of hydrochloric acid when the reaction had proceeded for 15 hours. At what time was the reaction just complete? On the grid above, draw a line to show how the concentration of hydrochloric acid changes with time when the reaction takes place at a higher temperature. Hydrochloric acid is formed when hydrogen chloride gas is dissolved in water. Draw a dot-and-cross diagram to show the electron arrangement in a molecule of hydrogen chloride. Show only the outer electron shells. Show hydrogen electrons as x. Show chlorine electrons as ●.
6. Chemical reactions  →  6.2. Rate of reaction
11. Organic chemistry  →  11.4. Alkanes
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6
Sulfur burns in air to form sulfur dioxide. Is sulfur dioxide an acidic or basic oxide? Give a reason for your answer. Sulfur dioxide is an atmospheric pollutant. Explain why sulfur dioxide in the atmosphere can erode buildings made of limestone. Sulfur dioxide reacts with oxygen to form sulfur trioxide. Sulfur trioxide can be made in the laboratory using the apparatus shown below. Sulfur trioxide has a melting point of 17 °C and a boiling point of 45 °C. ice sulfur trioxide crystals sulfur dioxide oxygen platinum catalyst concentrated sulfuric acid Suggest one safety precaution when carrying out this experiment. What is the purpose of the platinum catalyst? Complete the symbol equation for the reaction. 2SO2 + → SO3 Suggest why the sulfur trioxide is collected in a fl ask surrounded by ice. When 64 g of sulfur dioxide react with excess oxygen, 80 g of sulfur trioxide is formed. Calculate the mass of sulfur trioxide formed from 160 g of sulfur dioxide. mass = g Sulfur trioxide reacts with water to form sulfuric acid. A student used the apparatus shown below to determine the concentration of a solution of sodium hydroxide. sulfuric acid sodium hydroxide + indicator Which one of these pieces of apparatus should the student use to put 25.0 cm3 of sodium hydroxide into the fl ask. Tick one box. beaker measuring cylinder test-tube volumetric pipette How would the student know when the sulfuric acid had neutralised the sodium hydroxide? Clean air contains mainly nitrogen, noble gases, oxygen and water vapour. A teacher left a beaker of concentrated sulfuric acid open to the air for a week. After a week, the concentration of sulfuric acid in the beaker had decreased. at the start after one week concentrated sulfuric acid Explain these results by referring to one or more of the substances present in the air.
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
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7
Describe the properties of chlorine, bromine and iodine. In your answer, include the trends in: ● their state, ● their colour, ● their reactivity. A molecule of chlorine can be written as Cl – Cl. Which one of the following words describes this molecule? Put a ring around the correct answer. diatomic giant ionic monatomic Draw the electronic structure of a fl uorine atom. The equation below describes the reaction of a halogen with a halide. Br2 + 2KI → I2 + 2KBr Write a word equation for this reaction.
8. The Periodic Table  →  8.3. Group VII properties
11. Organic chemistry  →  11.4. Alkanes
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